/*
 * CVS identifier:
 *
 * $Id: SubbandSyn.java,v 1.25 2001/07/26 08:54:59 grosbois Exp $
 *
 * Class:                   SubbandSyn
 *
 * Description:             Element for a tree structure for a description
 *                          of subband for the synthesis side.
 *
 *
 *
 * COPYRIGHT:
 * 
 * This software module was originally developed by Raphaël Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 * 
 * Copyright (c) 1999/2000 JJ2000 Partners.
 * */
package jj2000.j2k.wavelet.synthesis;

import jj2000.j2k.wavelet.*;

/**
 * This class represents a subband in a tree structure that describes the
 * subband decomposition for a wavelet transform, specifically for the
 * syhthesis side.
 *
 * <p>The element can be either a node or a leaf of the tree. If it is a node
 * then ther are 4 descendants (LL, HL, LH and HH). If it is a leaf there are
 * no descendants.</p>
 *
 * <p>The tree is bidirectional. Each element in the tree structure has a
 * "parent", which is the subband from which the element was obtained by
 * decomposition. The only exception is the root element which has no parent
 * (i.e.it's null), for obvious reasons.</p>
 * */
public class SubbandSyn extends Subband {

    /** The reference to the parent of this subband. It is null for the root
     * element. It is null by default.  */
    private SubbandSyn parent;

    /** The reference to the LL subband resulting from the decomposition of
     * this subband. It is null by default.  */
    private SubbandSyn subb_LL;

    /** The reference to the HL subband (horizontal high-pass) resulting from
     * the decomposition of this subband. It is null by default.  */
    private SubbandSyn subb_HL;

    /** The reference to the LH subband (vertical high-pass) resulting from
     * the decomposition of this subband. It is null by default.
     * */
    private SubbandSyn subb_LH;

    /** The reference to the HH subband resulting from the decomposition of
     * this subband. It is null by default.  */
    private SubbandSyn subb_HH;

    /** The horizontal analysis filter used to recompose this subband, from
        its childs. This is applicable to "node" elements only. The default
        value is null. */
    public SynWTFilter hFilter;
       
    /** The vertical analysis filter used to decompose this subband, from its
        childs. This is applicable to "node" elements only. The default value
        is null. */
    public SynWTFilter vFilter;

    /** The number of magnitude bits */
    public int magbits = 0;

    /**
     * Creates a SubbandSyn element with all the default values. The
     * dimensions are (0,0) and the upper left corner is (0,0).
     * */
    public SubbandSyn() { }

    /**
     * Creates the top-level node and the entire subband tree, with the
     * top-level dimensions, the number of decompositions, and the
     * decomposition tree as specified.
     *
     * <p>This constructor just calls the same constructor of the super
     * class.</p>
     *
     * @param w The top-level width
     *
     * @param h The top-level height
     *
     * @param ulcx The horizontal coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param ulcy The vertical coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param lvls The number of levels (or LL decompositions) in the tree.
     *
     * @param hfilters The horizontal wavelet synthesis filters for each
     * resolution level, starting at resolution level 0.
     *
     * @param vfilters The vertical wavelet synthesis filters for each
     * resolution level, starting at resolution level 0.
     *
     * @see Subband#Subband(int,int,int,int,int,
     * WaveletFilter[],WaveletFilter[])
     * */
    public SubbandSyn(int w, int h, int ulcx, int ulcy, int lvls,
                     WaveletFilter hfilters[], WaveletFilter vfilters[]) {
        super(w,h,ulcx,ulcy,lvls,hfilters,vfilters);
    }
    
    /**
     * Returns the parent of this subband. The parent of a subband is the
     * subband from which this one was obtained by decomposition. The root
     * element has no parent subband (null).
     *
     * @return The parent subband, or null for the root one.
     * */
    public Subband getParent() {
        return parent;
    }

    /**
     * Returns the LL child subband of this subband.
     *
     * @return The LL child subband, or null if there are no childs.
     * */
    public Subband getLL() {
        return subb_LL;
    }

    /**
     * Returns the HL (horizontal high-pass) child subband of this subband.
     *
     * @return The HL child subband, or null if there are no childs.
     * */
    public Subband getHL() {
        return subb_HL;
    }

    /**
     * Returns the LH (vertical high-pass) child subband of this subband.
     *
     * @return The LH child subband, or null if there are no childs.
     * */
    public Subband getLH() {
        return subb_LH;
    }

    /**
     * Returns the HH child subband of this subband.
     *
     * @return The HH child subband, or null if there are no childs.
     * */
    public Subband getHH() {
        return subb_HH;
    }

    /**
     * Splits the current subband in its four subbands. It changes the status
     * of this element (from a leaf to a node, and sets the filters), creates
     * the childs and initializes them. An IllegalArgumentException is thrown
     * if this subband is not a leaf.
     *
     * <p>It uses the initChilds() method to initialize the childs.</p>
     *
     * @param hfilter The horizontal wavelet filter used to decompose this
     * subband. It has to be a SynWTFilter object.
     *
     * @param vfilter The vertical wavelet filter used to decompose this
     * subband. It has to be a SynWTFilter object.
     *
     * @return A reference to the LL leaf (subb_LL).
     *
     * @see Subband#initChilds
     * */
    protected Subband split(WaveletFilter hfilter, WaveletFilter vfilter) {
        // Test that this is a node
        if (isNode) {
            throw new IllegalArgumentException();
        }

        // Modify this element into a node and set the filters
        isNode = true;
        this.hFilter = (SynWTFilter) hfilter;
        this.vFilter = (SynWTFilter) vfilter;

        // Create childs
        subb_LL = new SubbandSyn();
        subb_LH = new SubbandSyn();
        subb_HL = new SubbandSyn();
        subb_HH = new SubbandSyn();

        // Assign parent
        subb_LL.parent = this;
        subb_HL.parent = this;
        subb_LH.parent = this;
        subb_HH.parent = this;

        // Initialize childs
        initChilds();

        // Return reference to LL subband
        return subb_LL;
    }
    /** 
     * This function returns the horizontal wavelet filter relevant to this
     * subband
     *
     * @return The horizontal wavelet filter
     * */
    public WaveletFilter getHorWFilter(){
        return hFilter;
    }

    /** 
     * This function returns the vertical wavelet filter relevant to this
     * subband
     *
     * @return The vertical wavelet filter
     * */
    public WaveletFilter getVerWFilter(){
        return hFilter;
    }
}
